This invention relates to a control apparatus for controlling one or both of the fuel injection and the ignition timing of an internal combustion engine. More particularly, it relates to a control apparatus for an internal combustion engine which does not employ an air intake pressure sensor or an air intake rate sensor.
Conventional control apparatuses for internal combustion engines sense various parameters of engine operation, such as coolant temperature, air intake pressure, the engine rotational speed, and the oxygen concentration in the exhaust gas. The ignition timing and the fuel injection amount are then calculated based on a predetermined mathematical relationship among the sensed parameters. The relationship, which is usually stored in the form of a table in a read-only memory, gives the optimal fuel injection amount and ignition timing for a baseline engine. However, due to manufacturing discrepancies among mass-produced engines, the operating characteristics of the engine which is actually being controlled may differ significantly from those of the baseline engine. Furthermore, even if the engine being controlled initially has the same characteristics as a baseline engine at the time of manufacture, due to wear of the engine parts with the passage of time, the operating characteristics can change so as to differ from those of the baseline engine. Therefore, the relationship which is stored in the memory may not give the proper ignition timing and fuel injection amount for the engine being controlled, so proper control of the engine can not be carried out, resulting in a decrease in engine performance.